The exodus started as early as 10 a.m., when a steady stream of vehicles headed up Route 6 west toward Boston. Traffic leaving the Cape became heavier around 11 a.m., with backups extending 1 to 3 miles east of the Cape Cod Canal, according to Michael Verseckes, a spokesman for the state Department of Transportation.

“I think it’s just because it’s overcast,” Verseckes said.

By 6 p.m., the RideWise smartphone application showed traffic moving at 13 miles an hour between Route 130 and the Sagamore Bridge.

Some travelers took to Twitter to express concerns and frustration.

“Cape traffic is so bad ... I should’ve brought the newspaper and a bucket of popcorn to pass the time away,” wrote @ARCurran_28 just after 1 p.m.

“Cape traffic is UNREAL right now,” @caittlyna tweeted at 4:22 p.m., following the message with two emoticons of monkeys covering their eyes.

After checking out of Cape Cod Inn earlier in the day, Eric Martel said the gloom had changed his travel plans.

“We wanted to go to the beach today, but the weather stinks,” said Martel, 29, of Marlborough. “We’re just going to leave instead.”

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